In recent years the wiring of buildings and of business offices with both power and telephone cables laid under the floor carpeting has become a multi-million dollar industry. A number of companies, such as AMP and T & B, have developed wiring systems, both power and telephone, for this purpose. But so far all power systems presently on the market have one or more drawbacks. In particular, the previously available undercarpet power systems tend to be complicated, expensive and/or difficult to install.
The previously available power cable itself comprises three or more thin flat copper conductors (each of the order of 5 to 20 mils thick and about a half-inch to an inch wide) insulated by laminated layers of a tough polymer such as Mylar, DUPONT trademark. Some termination systems make contact to the cable conductor by insulation displacing contacts (IDC) of which the T & B "Dragon Tooth" connector is a leading example. However, because the insulation (e.gg. Mylar) is usually chosen to have toughness and high resistance to cut-through, these IDC contacts require high forces to apply them or else they are not completely stable and secure.
A second problem with existing power systems is the complexity of the installation procedure and the expense of the applicator tooling. One attempt to overcome this second problem is shown in U.S. Pat. No. 4,241,498. While the method and device shown in this patent gave outstanding electrical results, the considerable thickness of the termination make it impossible to use for undercarpet wiring.
Another problem with existing undercarpet power wiring systems is that they are susceptible to corrosion and the deleterious effects of moisture and water. Mylar in particular is attacked by the alkali of concrete floors (where the pH may approach 13). The effects of corrosive reagents and/or other chemicals in the presence of water and electricity has caused a number of failures in the field.
There is also the problem with existing systems of maintaining electrical continuity of the top shield, generally of steel foil, which is required by the electrical code for mechanical protection and to insure that a reliable "ground" connection is carried to the output power receptacles.